2.1 Sympathomimetic Pharmaceuticals
Sympathomimetic compounds, as the name implies, exert biological effects similar to those produced by activation of the sympathetic nervous system. For example, the pharmaceutical compound pseudoephedrine acts as an indirect sympathomimetic agent by causing adrenergic nerve endings to release norepinephrine, thereby stimulating .alpha. and .beta. norepinephrine receptors, particularly in blood vessels of the upper respiratory tract. This, in turn, results in vasoconstriction and shrinkage of swollen tissues in the sinuses and nasal passages.